It depends.
If your item cost less than $20 CDN (about $18 USD) neither duty nor tax is applicable. There will be no 'brokerage ' or 'service' fee.
Most Chinese sellers use the postal system, since China Post heavily subsidizes shipping overseas.
Canada Post and CBSA have a policy of ignoring any personal imports valued at less than $100 because it costs more to assess than they could possibly collect. Common sense from your public service at work.
But.
If the item cost more than $20 and/or is bulky, the chances of it being assessed are higher. If it is Canada Post will charge you $9.95 in addition to the applicable duty and provincial sales tax (GST/PST/HST).
So.
If it's over $20 CDN, assume you will pay duty, tax and a service fee. Then you will be happy if you are not charged.
